f(x)?

[prog_tom]

what is f(x)? I noticed it's a function, but can anyone explain it to me? What am I suppose to do with f(x)=79x+y+7z; or something like that? How to graph that onto a real number line?

[[Digital-X-Treme]]

Originally posted by prog_tom
what is f(x)? I noticed it's a function, but can anyone explain it to me? What am I suppose to do with f(x)=79x+y+7z; or something like that? How to graph that onto a real number line?

f(x) is a user defined function, with parameter x. You could equally have g(x), k(x), p(z), mFunc(s, t)... You define the function, and the parameters.

The actual function you specified would have three parameters, as it contains x, y and z variables. So:

f(x, y, z)=79x+y+7z

You can then say f(1,2,4) = 109, as 79*1 + 2 + 7 * 4 = 109.

[noble]

the function that he specified is not necessarily f(x,y,z)

f(x) simply says that it's a function which has x as a dependant
variable.

f(x) = 79x+y+7z, z and y could be constants if it's a function
with respect to x

[[Digital-X-Treme]]

Originally posted by noble
the function that he specified is not necessarily f(x,y,z)

f(x) simply says that it's a function which has x as a dependant
variable.

f(x) = 79x+y+7z, z and y could be constants if it's a function
with respect to x

Yeah, possibly, but generally, letters nearer the end of the alphabet are used as variables i.e. x, y, z, while letters such as A, B, C are used to represent constants.

[noble]

the reason why i said that y and z are constants is because
f(x) itself is also a variable.... usually y
if f(x) is a variable which depends on x, then if f(x) = y or z
it's odd for it to be expressed in terms of y and z

[nishantp]

Originally posted by prog_tom
what is f(x)? I noticed it's a function, but can anyone explain it to me? What am I suppose to do with f(x)=79x+y+7z; or something like that? How to graph that onto a real number line?

There are 4 variables in that equation. Im only in grade 10 math, but without knowing some more of those values, i don't think its a valid equation for a line (linear relation).

[darthy]

I believe f(x) = "whatever" is what is called the relation of a recursively defined function.

ALong with the relations there should be what is called stopping conditions such as f(1) = 0 and f(0) = 0.

an anology of this would be the towers of hanoi puzzle where the stopping condition is Hanoi(1) = 1, the relation being hanoi(x) = (2^x) -1

[thinktank2]

Darthy, You are confusing yourself.

If f(x) is defined as

f(x) = 4x + 3x^2 + 1

then it is not a recursive function.

f(x) = 4*f(x-1) is a recursive function.

[[Digital-X-Treme]]

There seems to be a lot of confusion in this thread. Look here for additional information on functions, notation etc. http://mathworld.wolfram.com/Function.html

[darthy]

My aplogies ThinkTank, you are correct.

It's a long time since I have studied computer science!!!!


Like your example illistrates a recursive function is one that although looks as though it is defined in terms of itself, it is in fact defined by a simpler version of themselves (stopping condition).